What would couse a cat to lose its hair?

We have a black male cat called Sabbath and a black and white female named Crystal. We used to have about a dozen but had to get rid of most. It could be caused from over grooming due to stress, allergies, lack of light, ringworm, hormone inbalance, flea infestation or vitamin deficensy. It is rather hard to treat unless you know what the real cause is. Good luck to you!

If the cat lays on plastic he could be allergic to the plastic. We had a cat that developed sores around her mouth because she was allergic to the plastic bowl. They went away after we switched the bowl to metal. Also it could be an allergic reaction to foods, are there bumps under the cat's fur? Ours had bumps under her fur and would pull the fur out because of an allergy to her food.

A lot of times if a cat has a reaction to fleas they over groom. Also, if they are over stressed, some cats will over groom then too. I've had both

Fleas, stress, maybe ringworm? If it's ringworm, it needs to be treated. it's not particularly dangerous, but it's very contagious.

There are many possibilities. Fleas or an allergic reaction to them could get them started. then there are mites.. or stress.. Or like my little kitten a couple years ago.. ?? Nothing that we could find.. She was 4 weeks old and lost all her outer coat.. all she was left with was peach fuzz. Cute as heck.

My cat once lose all of its fir, yes all of its fir. Later on I know that he lost his fur due to eating white popinac. After a month he regain his fir, but more than he usually have